If you're a 5'6"-tall, 130-pound, 35-year-old female who exercised three times per week, your daily calorie intake should be no more than 1800 calories. Of course, this probably doesn't describe you exactly, so if you want to calculate what your daily intake should be, go here.

It's one thing to know how many calories you should be eating in one day. Understanding how much food those calories correspond to is a bit more difficult. In order to get an idea of what a 300-400 calorie meal looks like, check out these pictures. The good news is that you can probably afford to have meals a bit larger than these. The bad news is that the average American eats meals much larger than these.